Double-corrugated sheet-iron.



K. KNUTSON. (DOUBLE GOBRUGATED SHEET IRON. APrLIo'ATxoN FILED DEO. '1, 190g.

948,7133." Patented Feh, 1910.

3 Figiy aristas.

AKNUT KNUTSON, OF CHRISTIANIA, NORWAY.

DOUBLE-COREUGATED SHEET-IRON.

Specification of Letters Patent.

Ettatciited Feb.. t3, itth Application filed .Decemberv 7, 1908. Serial No. 4661396.

T o atl whom 'it may concern:

Be it known that I, KNUT KNU'rsoN, a citizen of the Norwegian Kingdom, and resi- `dent ot' Christiania, Norway, have invented an Improved Double-Corrugated Sheet-Iron, of which the following is a specification.

The subject ot' this invention is a new type of corrugated sheet iron, whose proile is such that the corrugations are bent up and down alternately. In this way the height of the profile is doubled and the moment of resistance is made LG-times as great as before, while the weight remains the saine as that ofsheet iron ot the saine number of the oldtype. i

The accompanying drawing shows the proile of the new type of corrugated sheet iron.

Figures l, 3 and 4, show the manner ot' developing the same from the old profile. VFig.2 shows the sheet iron. v In the case of sheet iron made according to the chain dotted line in Fig. Lthe deeper Athe profile is made, the greater is the stress on the material at the top of the eorrugation and in the wall of the corrugation, for which reason the high profiled sheets which are made at present, must bel of considerable thickness.

A deep corrugation requires a. siilticient thickness at the top ot the corrugation in order to withstand the bending stress and not to be pressed flat, and it is alsoA necessary for the vertical wall to be made thick in order to otter sutiicient resistance to the trans' verse forces. This fact is recognized today in the manufacture of corrugated sheet iron, and the higher the profile the thicker are the sheets from which it is rolled.

gi one compares curves 2 and 3 it is evide t that the radii for both are equalwhile in curve l the radii are twice as large as in Figs. 2 and 3. The elastic strength istherefore twice as great in the profiles 2 and 3 las in profile 1. The S curve made in this Way gives the vertical wall the stitiness necessary to absorb the transverse forces. It is impossible for the vertical wall to buckle, how ever thin, when this S spring is interposed.

The following example Will illust-rate the profile ofthe new kind of difference in strength between the new and old types of sheet iron. It' two standard corrugated sheets are fastened together so that the tops of the corrugations are symmetrical to the axis which is between both sheets, Fig. 3., then the moment of resistance becomes 3.2 times that of a single sheet. The weight however has been doubled. if one imagines the alternate upper and lower corrugations removed Fig. 1, the prole shown in Fig. 2 is obtained. The moment ot' resistance of this new profile is exactl lialic that of the former (Fig. 3) and theretore 1.6 times as great as the old type of corrugated sheet iron, while the weightremains the same. In other words the qld type of corrugated sheet iron did not give a maxi- .iniim moment ot' resistance while the new type does. This type of sheetiron can be used for other purposes than the old sort, t'or instance for tloors and ceilings.`

Owing to the increased strength greater spans can be used and the supports need be fewer.

The new sheet iron requires less filling material as there are not so many corrugations. This new kind of sheetiron is very suitable tor unsupported roots of buildings and similar purposes.

Having fully described my invention, what I claim and desire to secure by Letters Patent is l. Sheet iron doubly corrugated, that is to say, the sheet being provided with corrugations projecting alternately from opposite sides thereof, the bases ot the said corrugations being united on a. double reverse curve,

substantially as described and shown.

2. Sheet iron doubly corrugated, that is to say, the sheet being provided with corruga tions projecting alternately from opposite sides thereof, the bases. of the said corrugations being united on curves of any desired shape, substantially as described and shown.

In testimony whereof I have hereunto set my hand in the presence of two subscribing witnesses. y

' KNUT KNUTSON. Witnesses:

OLcF BUCK, M. LGER. 

